A few of my beet plants (~5%) have these odd skin-like bubbles forming on one or two of their leaves. When I pop them they're filled with these patches of black particles (possibly dead pests of some sort?). Any ideas what they're from, and/or if they're malicious?
I'm in the high desert in Albuquerque, NM where it's been oscillating between intense sun, cool (40s-50sF) nights, and spotty rain. I have had an outbreak of leaf miners on the beet leaves and nearby on some cauliflower and spinach leaves. Could this be related?